package com.example.Utils;

import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.thymeleaf.util.StringUtils;

import java.io.*;

public class DownloadUtils {


    public static void main(String[] args) {
        String urlPath = "https://tjg.gzhuibei.com/a/1/41845/2.jpg";
        downloadPicture(urlPath,"tjdPic","/Users/zhaoyuyang/Downloads/");
    }

    public static String downloadPicture(String urlPath, String fileName, String filePath) {
        if (StringUtils.isEmpty(urlPath)) {//可能混杂一些空链接.需要处理
            return "";
        }
        CloseableHttpClient httpClient = null;
        InputStream inputStream = null;
        File file = null;
        try {
            httpClient = HttpClients.createDefault();
            HttpGet method = new HttpGet(urlPath);
            HttpResponse result = httpClient.execute(method);
            inputStream = result.getEntity().getContent();
            //得到图片的二进制数据,以二进制封装得到数据,具有通用性
            byte[] data = readInputStream(inputStream);
            //new一个文件对象用来保存图片,默认保存当前工程根目录
            File isexits = new File(filePath);
            if (!isexits.exists()) {
                isexits.mkdirs();
            }
            /**
             *
             * 问题解决:outputstream流不能直接创建文件夹,所以在直接写不存在的文件夹的时候会出现问题,这个时候在前面进行一个文件夹是否存在的判断,
             * 若存在,直接存储不会出现问题,
             * 若不存在,需要先创建一个文件夹才可以
             */
            File imageFile = new File(filePath + File.separator + fileName + ".jpg");
            //创建输出流
            FileOutputStream outStream = new FileOutputStream(imageFile);
            //写入数据
            outStream.write(data);
            //关闭输出流
            outStream.close();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                inputStream.close();
            } catch (IOException e) {

            }
            try {
                httpClient.close();
            } catch (IOException e) {

            }
            return filePath + File.separator + fileName + ".jpg";
        }

    }

    public static byte[] readInputStream(InputStream inStream) throws Exception{
        ByteArrayOutputStream outStream = new ByteArrayOutputStream();
        //创建一个Buffer字符串
        byte[] buffer = new byte[1024];
        //每次读取的字符串长度,如果为-1,代表全部读取完毕
        int len = 0;
        //使用一个输入流从buffer里把数据读取出来
        while( (len=inStream.read(buffer)) != -1 ){
            //用输出流往buffer里写入数据,中间参数代表从哪个位置开始读,len代表读取的长度
            outStream.write(buffer, 0, len);
        }
        //关闭输入流
        inStream.close();
        //把outStream里的数据写入内存
        return outStream.toByteArray();
    }
}
